This invention relates to the hydrometallurgical processing of ores. More particularly, it relates to an improvement in processing ores hydrometallurgically whereby the recovery of desired values from the ores is substantially increased. Still more particularly, it relates to a novel procedure for separating mineral matter from ores containing metallic values whereby the loss of metallic values, normally encountered in solid-liquid separations, is substantially reduced.
For effective recovery of dissolved metallic values from solid mineral matter, it is conventional to make a series of liquid-solid separations following repetitive stages of washing of the solid phase with counterflow of solution removed from each subsequent stage of liquid-solid separation, washing being done with water and/or barren solution prior to the last stage. Barren solution is commonly known as the solution remaining after the metallic values have been recovered by processes such as precipitation or electrolytic separation. The most efficient methods to date have involved the application of one of the following equipment systems: countercurrent thickening circuits, self-cleaning filters or solid-bowl centrifuges. By these methods, however, a substantial amount, usually from about 8% to 15%, of metallic values is removed with the solid mineral matter. Frequently, with ores containing a high percentage of clays, fine silicate particles and the like, the percentage of metallic values removed with the mineral matter well exceeds 15%. This is because such constituents either absorb a relatively large amount of the metallic values solution and/or cannot be effectively washed and dewatered. When the foregoing methods are utilized, such constituents are generally separated with the solid mineral matter, carrying metallic values with them. The metallic values lost in the liquid-solid separation steps have not previously been economically available for recovery through subsequent processing.
In fact, separation of the dissolved metallic values from the undissolved mineral matter has meant extremely high capital costs and operating costs per daily ton of plant capacity. Further, a method of separating the dissolved metallic values may be incompatible with other processing steps. For example, in potash metallurgy, a continuous countercurrent decantation (CCD) thickening circuit is not economically combinable with amine flotation of mineral matter particles from particles of potash.
It is an object of the present invention to avoid the significant loss of metallic values associated with liquid-solid separations.
It is also an object of the present invention to provide a method of separating the dissolved metallic values from undissolved mineral matter which affords for lower capital costs per daily ton of plant capacity or, similarly, a higher recovery of metallic values for comparable capital costs per daily ton of plant capacity.
A further object of the present invention is to provide a method of separating dissolved metallic values from undissolved mineral matter which is economically combinable with other heretofore incompatible processing steps.
Another object of the present invention is to provide a process for recovering metallic values from mineral matter which affords better washing action through continuous agitation during separation, which cannot be achieved by conventional practices involving thickeners, centrifuges and/or filters.
Another object of the present invention is to provide a method of obtaining a better contact between particles bearing metallic values and solution through continuous agitation during separation, which affords a better opportunity for leaching the metallic values.
A further object of the present invention is to provide a process of obtaining metallic values from mineral matter which has a fewer number of washing and separation steps than utilized with conventional practices for equivalent yields.